Maintaining the self renewal capacity of a stem cell or initiating its differentiation is a fundamental decision for developmental processes and regeneration that needs to be orchestrated precisely. The ancestral freshwater polyp Hydra is a unique model system for axial patterning and regeneration research. This radially-symmetric cnidiarian with outstanding regenerative capacities was found to establish a primary body axis in a Wnt/ß-Catenin dependent manner. This crucial pathway initiates head organizer formation and hence has a significance for positional information along the single body axis.
In the context of head regeneration, ß-Catenin was previously demonstrated to act as early response gene within the first 30 minutes after decapitation.
Here, I demonstrate that also foot regeneration depends on nuclear ß-Catenin activity and that a block of ß-Catenin responsive transcription represses the terminal differentiation of head and foot. Furthermore ß-Catenin and ß-Catenin induced target gene expression remains upregulated in head and foot regenerates when ß-Catenin responsive transcription is pharmacological inhibited by iCRT14.
I therefore propose, that a gene regulatory ß-Catenin activity is required for a transition from pre-patterning to position-specific differentiation despite of the regenerating site. Additionally, the spatiotemporal differences of transcriptional and translational profiles of the head specific factor HyBra1 provide evidence that a translational control mechanism is involved in the onset of a position-dependent differentiation program.